Conductive materials, for example, metals such as copper have a high surface energy. Consequently, when depositing these conductive materials at high temperatures (e.g., about 100 degrees Celsius or greater), for example, using physical vapor deposition (PVD) or similar techniques, the conductive materials tend to agglomerate on a surface of a substrate and/or fail to fill a feature formed in a surface of a substrate because of the high surface energy of the conductive materials. Some solutions for this wetting problem include depositing a wetting layer to provide a lower interfacial energy between the conductive materials and the wetting layer on which the conductive materials are deposited than would otherwise be present if the conductive materials were deposited directly onto the surface of the substrate. Unfortunately, the inventors have discovered that such wetting layers can undesirably result in higher resistivity and/or lower surface diffusion rates of the conductive materials.
Accordingly, the inventors have provided improved methods for depositing conductive materials on a substrate.